USL3633 Datasheet PDF - Unisonic Technologies
| Part Number | USL3633 | |
| Description | NON-ISOLATED BUCK OFFLINE LED DRIVER | |
| Manufacturers | Unisonic Technologies | |
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UNISONIC TECHNOLOGIES CO., LTD
USL3633
Preliminary
LINEAR INTEGRATED CIRCUIT
NON-ISOLATED BUCK
OFFLINE LED DRIVER
DESCRIPTION
The UTC USL3633 is a high performance, high precision and
low cost constant current LED driver for non-isolated buck
application. The device operates in critical conduction mode and
is suitable for 85V~265V universal input offline LED lighting. It
operates in critical conduction mode, the output current does not
change with the inductance and LED output voltage.
The UTC USL3633 integrates a 600V power MOSFET. It can
achieve excellent constant current performance with very few
external components, so the system cost and size are minimized.
The UTC USL3633 offers rich protection functions to improve
the system reliability, including LED open circuit protection, LED
short circuit protection, VCC under voltage protection, CS resistor
short circuit protection and thermal regulation function.
FEATURES
* Critical conduction mode operation
* Internal 600V Power MOSFET
* Ultra low operating current
* No auxiliary winding
* ±5% LED output current accuracy
* LED short protection
* LED open protection
* VCC under voltage protection
* Current sensing resistor short protection
* Thermal regulation function
ORDERING INFORMATION
Ordering Number
USL3633G-S08-R
Package
SOP-8
SOP-8
Packing
Tape Reel
USL3633G-S08-R
(1)Packing Type
(2)Package Type
(3)Green Package
(1) R: Tape Reel
(2) S08: SOP-8
(3) G: Halogen Free and Lead Free
MARKING
www.unisonic.com.tw
Copyright © 2015 Unisonic Technologies Co., Ltd
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USL3633
Preliminary
LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
Over Voltage Protection
The over voltage protection can be programmed by the ROVP pin resistor. The ROVP pin voltage is 0.5V.
When the LED is open circuit, the output voltage increases gradually, and the demagnetization time gets shorter.
The demagnetization time at OVP---- Tovp can be calculated by the open circuit protection voltage:
TOVP
≈
L IPK
VOVP
Where，
Vovp is the open circuit protection voltage
And then the Rovp resistor value can be calculated by the equation:
ROVP ≈ 19 Top 106
(kΩ)
Protection Function
The UTC USL3633 offers rich protection functions to improve the system reliability, including LED open/short
protection, CS resistor short protection, VCC under voltage protection, thermal regulation. When the LED is open
circuit, the system will trigger the over voltage protection and stop switching.
When the LED short circuit is detected, the system works at low frequency (about 5kHz), and the CS pin turn off
threshold is reduced to 200mV. So the system power consumption is very low. At some catastrophic fault condition,
such as CS resistor shorted or inductor saturated, the internal fast fault detection circuit will be triggered, the system
stops switching immediately.
After the system enters into fault condition, the VCC voltage will decrease until it reaches the UVLO threshold,
then the system will re-start again. If the fault condition is removed, the system will recover to normal operation.
Thermal Regulation
The UTC USL3633 integrates thermal regulation function. When the system is over temperature, the output
current is gradually reduced; the output power and thermal dissipation are also reduced. The system temperature is
regulated and the system reliability is improved. The thermal regulation temperature is set to 150°C internally.
PCB Layout
The following rules should be followed in UTC USL3633 PCB layout:
Bypass Capacitor
The bypass capacitor on VCC pin should be as close as possible to the VCC Pin and GND pin.
ROVP Pin
The ROVP resistor should be as close as possible to the ROVP Pin.
Ground Path
The power ground path for current sense should be short, and the power ground path should be separated from
small signal ground path before connecting to the negative node of the bulk capacitor.
The Area of Power Loop
The area of main current loop should be as small as possible to reduce EMI radiation, such as the inductor, the
power MOSFET, the output diode and the bus capacitor loop.
NC pin
The NC pin should be connected to GND (pin1).
Drain Pin
To increase the copper area of DRAIN pin for better thermal dissipation. However too large copper area may
compromise EMI performance.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R103-097.b
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for USL3633 electronic component. |
| Information | Total 6 Pages | |
| Link URL | [ Copy URL to Clipboard ] | |
| Download | [ USL3633.PDF Datasheet ] | |
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